已知函数f(x)=cos^2x+2tsinxcosx-sin^2x(1.)当t=1时,若f(a/2)=3/4,试求sin2a的值(2.)若函数f(x)在区间(π/12,π/6]上是增函数,求实数t的取值范围

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已知函数f(x)=cos^2x+2tsinxcosx-sin^2x(1.)当t=1时,若f(a/2)=3/4,试求sin2a的值(2.)若函数f(x)在区间(π/12,π/6]上是增函数,求实数t的取值范围
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已知函数f(x)=cos^2x+2tsinxcosx-sin^2x(1.)当t=1时,若f(a/2)=3/4,试求sin2a的值(2.)若函数f(x)在区间(π/12,π/6]上是增函数,求实数t的取值范围
已知函数f(x)=cos^2x+2tsinxcosx-sin^2x
(1.)当t=1时,若f(a/2)=3/4,试求sin2a的值
(2.)若函数f(x)在区间(π/12,π/6]上是增函数,求实数t的取值范围

已知函数f(x)=cos^2x+2tsinxcosx-sin^2x(1.)当t=1时,若f(a/2)=3/4,试求sin2a的值(2.)若函数f(x)在区间(π/12,π/6]上是增函数,求实数t的取值范围
f(x)=cos^2x+2tsinxcosx-sin^2x
=cos2x+tsin2x
1.t=1
f(x)=cos2x+sin2x
f(a/2)=cosa+sina=3/4 平方
1+sin2a=9/16 sin2a=7/16
2.f(x)=cos2x+tsin2x
=√(1+t^2)*sin(2x+φ) (其中tanφ=1/t)
f(x)的增区间 2kπ-π/2